# 2441. Largest Positive Integer That Exists With Its Negative

``````class Solution {
public int findMaxK(int[] nums) {

HashSet<Integer> numSet = new HashSet<>();
int maxK = -1;

// Adding all numbers to the set
for (int num : nums) {
}

// Iterating through the array to find the largest positive integer k
for (int num : nums) {
if (numSet.contains(-num) && num > 0) {
maxK = Math.max(maxK, num);
}
}

// Returning the result
return maxK;
}
}

``````

This Java code defines a method `findMaxK` within a class `Solution`. The purpose of this method is to find the largest positive integer `k` such that its negative counterpart `-k` exists in the given array `nums`.

Here’s a breakdown of how the code works:

1. Initialization:
• `HashSet<Integer> numSet = new HashSet<>();` creates a HashSet to store unique integers from the input array.
• `int maxK = -1;` initializes a variable `maxK` to `-1`. This variable will hold the largest positive integer `k` found in the array.
1. Adding numbers to the set:
• The first loop iterates through each element `num` in the `nums` array.
• Inside the loop, each `num` is added to the `numSet`. This ensures that the HashSet contains unique elements from the input array.
1. Finding the largest positive integer `k`:
• The second loop iterates through each element `num` in the `nums` array again.
• For each `num`, it checks if its negative counterpart `-num` exists in the `numSet` (i.e., if `-num` is present in the array).
• Additionally, it checks if `num` is positive (i.e., `num > 0`).
• If both conditions are true (i.e., if `-num` exists and `num` is positive), it updates `maxK` to the maximum of its current value and `num` using `Math.max(maxK, num)`. This ensures that `maxK` holds the largest positive integer `k` encountered so far in the array.
1. Returning the result:
• After looping through all elements in the array, the method returns the value of `maxK`, which represents the largest positive integer `k` found in the array for which its negative counterpart exists.

Overall, this method efficiently finds the largest positive integer `k` such that `-k` exists in the given array. If no such `k` is found, the method returns `-1`.